Abstract
Summary
A strain of Escherichia coli (strain WM-13), isolated from clinical material, was unlike the average wild-type strains of E. coli in that it could not grow in a synthetic salts-glucose medium. Growth could be obtained only by supplementing the medium with either methionine or p-aminobenzoic acid. Except for partial stimulation by leucine and α-aminobutyric acid, none of the other naturally occurring amino acids or B vitamins could support growth. Growth requirement was evident only when cultivation was carried out at 37°. At room temperature (21-24°) full growth was obtained in the unsupplemented minimal medium, but addition of homocysteine again imposed a requirement for methionine or p-aminobenzoic acid. The temperature-sensitive growth requirement is apparently the result of a deleterious reaction, involving homocysteine as a substrate, which interferes with the function of p-aminobenzoic acid in the biosynthesis of methionine.
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